What is best approach to handle exception for vari...

# ktor

[neworldlt]

What is best approach to handle exception for various accept content types? For example, if client asks application/json, I would like serialize exception using gson. If client asks text/html, then simple html page and for text/plain print only message.

[gildor]

check ContentNegotiation Ktor feature

[cy]

Something like that

install(ContentNegotiation) {
    gson {
        setPrettyPrinting()
    }
}
install(StatusPages) {
    exception<FileNotFoundException> { t ->
        call.respond(...)
    }
}

[neworldlt]

I have same solution. Problem is, I am needed different serialisers for normal response and errors

[neworldlt]

For example, my code is:

install(ContentNegotiation) {
        val converter = JacksonConverter(objectMapper)
        register(ContentType.Application.Json, converter)
    }
    install(StatusPages) {
        exception<BackendException> { cause ->
            call.respond(cause.responseStatus, cause.errorResponse)
        }
        exception<ValidationException> { cause ->
            call.respond(HttpStatusCode.InternalServerError, ErrorResponse(OTHER, message = cause.localizedMessage))
        }
    }

[neworldlt]

So, I want convert all ErrorResponse() to various content types. But for OK responses I would like support only application/json. It looks like separate ContentNegotiation for StatusPages. Is there any pattern to accomplish this?